1 Vol.:(0123456789) Scientific Reports | (2020) 10:20341 | https://doi.org/10.1038/s41598-020-77384-5 www.nature.com/scientificreports Plastic zone range of a roadway considering the creep effect Haidong Chen 1,2,3 , Xiangjun Chen 1,2,3* , Zhaofeng Wang 1 , Zhiqiang Li 1 & Fenghua An 1 The plastic zone range is an important parameter in the analysis of damage characteristics and the degree of damage to the rock surrounding a roadway. Based on the establishment of a plastic zone calculation model considering the creep effect, this paper obtains the characteristics of the change in the plastic zone damage range with time by solving the model. Additionally, the validity of the model is verified by field experiments. The research results can provide guidance for gas pressure measurement and gas drainage in coal mines. Gas disasters constitute the primary threat to safe production in many coal mines 1,2 . On the one hand, deter- mining the damage range of the plastic zone of the roadway can improve the accuracy of measuring the gas pressure (an important index in predicting the risk of coal and gas outbursts) in a coal mine; on the other hand, it can improve the sealing effect of the gas drainage borehole, thereby improving the gas drainage rate of the coal seam 3–6 . erefore, clearly establishing the damage range of the plastic zone of the roadway can indirectly prevent the occurrence of coal mine gas disasters. Many scholars have carried out research on the plastic zone of a roadway. Galin 7 considered that the shape of the plastic zone around the roadway in the uniform stress field is circular, and the formula for calculating the circular plastic zone was derived. Additionally, Chen et al. 8 established the boundary implicit equation for the plastic zone of a circular roadway. Abdel et al. 9 , Leitman and Villaggio 10 considered that the shape of the plastic zone of roadways located in non-uniform stress fields should be elliptical. Guo et al. 11 and Wang et al. 12 pointed out that the shape of the plastic zone of a roadway could be circular, elliptical or butterfly-shaped under different in situ stress conditions. Zhou and Wu 13 , Yang et al. 14 used a numerical simulation method to study the plastic zone range of a roadway under different stress conditions. e practice of mining shows that at constant stress, the creep of coal and rock will occur as time goes on; that is, the deformation of coal and rock will continue to grow with time 15–19 . Even under low stress conditions, the creep of coal and rock would also occur. Due to the creep effect, the plastic zone of a roadway will increase with time and finally approach a certain value. It can be seen that the previous research on the plastic zone of a roadway did not consider the creep effect of the surrounding rock of the roadway and thus cannot better guide engineering practice. In this paper, a plastic zone calculation model considering the creep effect was established to analyze the variation in the plastic zone damage range with time. e validity of the model is also verified by field experiments. Calculation model of the plastic zone of a roadway considering the creep effect Model assumptions. To obtain the specific range of the plastic zone of a roadway, some necessary practical assumptions are made to simplify the solution. e basic assumptions are as follows: (1) Since the axial length of the roadway is much larger than the radial width, the stress problem of the roadway section can be regarded as a plane strain problem. (2) e stress around the roadway is assumed to be uniform and the shape of the plastic zone of the roadway is assumed to be circular. (3) e failure of the plastic zone of the rock mass meets the Mohr–Coulomb yield criterion. (4) e stress distribution of any roadway section is shown in Fig. 1. Figure 1 shows the plastic zone, viscoelastic zone and initial stress zone. OPEN 1 School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China. 2 Henan Key Laboratory of Coal Green Conversion, Henan Polytechnic University, Jiaozuo 454000, Henan, China. 3 Collaborative Innovation Center of Coal Safety Production of Henan Province, Jiaozuo 454000, Henan, China. * email: [email protected]
Plastic zone range of a roadway considering the creep efect
Jun 18, 2023
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